Here's an interesting thought. US Bank put a lot of money into NW during BK to keep it going, one would assume they have a stake in NW now, as NW pays off the debt. Amex put a lot of money into DL during BK to keep it going, same deal.
If you attempt a merger, one of the companies is going to get the shaft and become the preferred credit card issuer for the combines FF program. How's that going to work?